The scope of my current R01 is to determine if red blood cell (RBC) hypoxia metabolic reprogramming mediated by adenosine and sphingosine 1 phosphate (S1P) (see our recent publications including Nature Medicine, JCI, Blood, Circulation, Nature Communications and Blood Advances) signalling network counteracts renal hypoxic damage and disease progression in chronic kidney disease (CKD), which is frequently driven by hypoxia. Down Syndrome (DS) is known associated with RBC alterations including macrocytosis and impaired redox homeostasis. However, the metabolic change in RBCs of DS patients was unknown prior to my successful collaboration with Dr. D?Alessandro, a Co-I on my current R01 and an investigator of the Linda Crnic Institute for DS in Denver, and director of the metabolomics core for the Human Trisome Project. With our combined expertise, using metabolomic profiling we revealed significant alterations in purine catabolites in RBCs from DS patients and mice. Intriguingly, in two independent DS cohorts (n=66), plasma adenosine and S1P levels were significantly reduced in both patients and mice with DS. Notably, renal disease in DS patients is not rare, especially for individuals entering the second decade of life, when the incidence of glomerular disease increases. Thus, our published studies and unpublished findings raise an intriguing hypothesis that altered RBC metabolic reprogramming mediated by reduced plasma adenosine and S1P is pathogenic to induce tissue hypoxia and multiple complications such as CKD, commonly associated with DS. To test this hypothesis, two aims are proposed: in AIM I, we will conduct human studies to determine if reduction of plasma adenosine and S1P signaling cascade underlies abnormal RBC metabolic reprogramming and decreased O2 delivery in DS patients. In AIM II, we will conduct mouse genetic studies using our newly developed RBC specific ADORA2B/SPHK1 knockouts and pharmacological preclinical studies to test the therapeutic effects of multiple FDA approved drugs to restore plasma adenosine and S1P levels and RBC metabolic reprogramming to promote tissue oxygenation and slow CKD progression in DS mouse models. Overall, the proposed studies in this present administrative supplement are built upon our recently published and unpublished findings and within the scope of my currently funded R01, which contains multidisciplinary highly innovative Omics approaches coupled with sophisticated mouse genetics and preclinical studies to focus on determining the pathogenic nature of abnormal RBC metabolic reprogramming in multiple life-threatening complications including CKD seen in DS. The proposed research is highly significant to identify potential early pathogenic biomarkers as intervenable targets to prevent and/or mitigate the severity of several comorbidities (including CKD) in DS. We believe our existing expertise in DS, metabolomics, RBC biology, proteomics and mouse genetics, along with support from the Linda Crnic Institute for DS have prepared us well to move our studies forward smoothly and quickly.